Main Features Features: Bluetooth chip / version: V/BLUETRUM 5.0 Speaker impedance: ? mm32? ± 15% Microphone sensitivity: + -40DB Wireless frequency: 2.405 GHZ-2.480 GHZ Battery indicator: rechargeable lithium polymer battery ma * 2 + 400ma Working temperature: -10-55 °C Power: DC5V Material: PC + ABS Supported file formats: A2DP, AVRCP, HSP, HFP Transmission power: level 2 Wireless distance: about 10 meters Play time: 2-3 hours (the charging box can charge the headset 4-5 times) Charging time: 1-2 hours